1. Field of the Invention
This invention relates to an engine mount and more particularly to an elastomeric engine mount which has different shear strengths in different horizontal directions.
2. Description of the Prior Art
Engine mounts mount an engine to the frame or cradle of a motor vehicle. The engine mount, besides securing the engine to the frame or cradle, should also isolate vibrations emanating from the engine and to compensate for drive line axial stresses which are exerted onto the engine.
An engine mount which includes a uniform elastomeric material that inherently provides different rates of elasticity is shear in different horizontal directions is desireable for the purposes of isolating vibrations and lowering costs.
One way of mounting the engine to isolate many vibrations is using an elastomeric material interposed between an upper and lower bracket of an engine mount. Such engine mounts, as disclosed in U.S. Pat. No. 4,151,822 issued to Tatsuhiko Miura on May 1, 1979, have elastomeric material bonded between an upper and lower bracket.
In addition, brackets are known which incorporate elastomeric materials with different resiliency rates in different horizontal directions. Extra amounts of rubber or harder rubber are placed into strategic locations in the bracket mount or cavities are formed therein to provide differing amounts of resiliency in different horizontal directions. One such elastic mount is disclosed in U.S. Pat. No. 2,958,526 to Ulderup et al on Nov. 1, 1960.
The joining of rubber components of different hardnesses, or the formation of cavities in a rubber block, in order to make an engine mount having different rates of resiliency in different directions make the engine mounts more expensive than necessary.